A well designed septic system will meet several basic requirements. First, the system will effectively collect, treat and transport wastewater throughout a drainfield. Second, the septic system will be simple to install and its components designed to reduce or eliminate installer error. Finally, a septic system will be easy to maintain. Poor design, improper installation and inadequate maintenance contribute to, or cause, poor drainage, blockages, or inefficient treatment of waste from a dwelling. Properly designed septic systems therefore integrate required performance attributes (i.e. collection, treatment and distribution of waste) with easy installation and a mechanism to simplify maintenance.
Several attempts have been made to accomplish such an integration. Particular attention has been given to the distribution of wastewater over a drainfield. Two systems that are available to distribute wastewater over a drainfield are equal distribution and serial distribution. An equal distribution system equally divides wastewater from a septic tank through a distribution box to several absorption trenches located in the drainfield. In a serial distribution system, wastewater travels through a series of linked absorption trenches in a sequential manner. Serial distribution systems are often used where the elevation of a septic tank is higher than the drainfield. Because wastewater travels sequentially through a serial distribution system, the linkages between two given trenches are important to the efficient operation of the septic system.
Conventional approaches linking two subsequent trenches in a serial distribution system are “step-down” and “drop-boxes.” The step-down can have three parts: an inlet, an elbow junction and a discharge arranged so that the elbow junction is elevated higher in the trench than either the inlet or discharge. This arrangement requires an upward incline leading up to the elbow junction of the step-down. In normal operation of step-down wastewater can accumulate in a trench pipe and flow upwards through the inlet, over the elbow junction, and through the discharge towards the next trench. When a step-down is improperly installed, or when the inlet and/or the elbow junction contains blockage, wastewater can flow backwards in the trench pipe causing undesirable backfill. A step-down is a closed system requiring precise linkages between the inlet, elbow junction and discharge. A “drop-box” can be a closed structure with an access lid, an inlet, outlets positioned close to the bottom of the drop-box, and an overflow outlet positioned close to the top. Wastewater enters the drop box and, after wastewater accumulates to rise to the height of the overflow outlets, is distributed to one or several subsequent trenches. Step-downs typically are constructed at the septic site, making proper installation imperative.
If installed improperly, both the step-down and drop-box can lead to malfunctions in the subsequent trenches. For step-downs, the possibility exists that the elbow junction will not properly accommodate for elevation changes between the two trenches. Less than precise measuring, cutting and fitting can lead to blockages and possible back-fill. When this occurs, the land owner or installer may incur substantial repair or replacements costs. Drop-boxes are typically prefabricated prior to installation and can unfortunately be easily installed backwards. For example, a pipe from a septic tank can be accidentally inserted into the overflow outlet of the drop-box. When water has accumulated the trenches, the wastewater will exit the overflow outlet first and causing undesirable backfill into the septic tank. Thus, improperly installed drop-boxes lead to back fill and blockages thus inhibiting the discharge of wastewater from the septic tank. Even when properly installed, both step-down and drop-box systems are subject to fatigue and excessive loads leading to ruptures or breaks. These breaks may disrupt wastewater flow and the delicate balance of a septic system. These attempts have failed to serve the primary goals of septic tank systems, i.e., to efficiently collect, treat and dispose of wastewater and to provided ease of maintenance and repair. The invention, however, efficiently collects and distributes wastewater in a septic system and can replace the step-down and drop-boxes currently used.